Protective relay test device

ABSTRACT

A test device for testing relays is provided. The test device includes a chassis and a plurality of generator components removably coupled to the chassis. Each of the plurality of generator components have a signal generator, a CPU to promote test signal generation by the signal generator, and an amplifier to amplify signals generated by the signal generator. The test device also includes a controller coupled to communicate with the plurality of generator components.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No. ______entitled “Programmable System for Device Testing and Control”, and U.S.patent application Ser. No. ______ entitled “Test Device for Signalingand Waveform Generation and Monitoring”, and U.S. patent applicationSer. No. ______ entitled “Protective Relay Test Device Having aHand-held Controller”, all filed one even date herewith and all of whichare incorporated herein by reference for all purposes.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

FIELD OF THE INVENTION

The present disclosure is directed to test equipment, and moreparticularly, but not by way of limitation, to a system and method fortesting protective electrical power relays.

BACKGROUND OF THE INVENTION

The electrical power system in the United States generates three-phasealternating current (AC) electrical power. Each power phase is 120degrees out of phase, plus or minus, with the other two power phases.The voltage of any phase oscillates sinusoidally between positivevoltage and negative voltage. It happens that three-phase powerdistribution provides an acceptable compromise between electricalgeneration and distribution efficiency and the expense and complexity ofpower distribution equipment.

It is more efficient to transmit electrical power at high voltage levelsthan at low voltage levels. Electrical power is generated as three-phaseAC power at moderate voltage levels in the 12 thousand volt (kV) to 25kV range. The voltage level is stepped up to the 110 kV to 1000 kV rangeusing a transformer for transmission over long transmission lines, henceminimizing transmission line power loss. The transmission line voltageis stepped down, using a transformer at a substation, to the 12 kV to 35kV range for local distribution. The local distribution voltage level isfurther stepped down through one or more transformer stages to provide120 volt AC power to the home and office. Special accommodations may bemade for manufacturing plant electrical power consumers.

Switchgear is employed to control the transmission systems. Theswitchgear may include circuit breakers, fuses, switches, and relays.Electrical power distribution protective relays, hereinafter referred tosimply as “relays,” monitor a variety of electric power distributionparameters and control circuit breakers based on the state or conditionof the electric power distribution parameters. For example, if too muchcurrent is being provided to a local distribution line, a relay maycommand a circuit breaker or switch gear to open, thus interrupting thesupply of electrical power to that local distribution line. Current,voltage level, frequency, phase, and other parameters may be monitoredby relays.

Relays vary in complexity from electromechanical devices monitoring asingle parameter to microprocessor controlled relays capable ofmonitoring many independent parameters concurrently. The relays arecapable of changing their behavior when reprogrammed for monitoringvarious characteristics of a power distribution system. For safe andreliable operation of the power distribution system it is necessary tothoroughly test relays in the manufacturer's plant, prior and uponinstallation in the power distribution system, and at periodic intervalsafter installation. Failures of the power distribution system, such asthe power blackout in the northeastern United States and southeasternCanada in 2003, can result in significant economic losses andinconvenience, and perhaps danger to those requiring special medicalservices dependent on electrical power distribution.

Testing of relays may be accomplished by emulating theoretical faultcharacteristics of a power distribution or generation system, therebyvalidating design elements associated with protection systems on a powerdistribution or generation system. This emulation consists of variousparameter characteristics associated with the power distribution systemduring a fault. Fault conditions, generated through emulation, aretherefore applied to the relay, and expected results are anticipated,validated or settings corrected for correct operation when the relay isapplied in an actual power distribution system.

SUMMARY OF THE INVENTION

The present disclosure provides, according to one embodiment, a testdevice for testing relays. The test device includes a chassis and aplurality of generator components removably coupled to the chassis. Eachof the plurality of generator components have a signal generator, a CPUto promote test signal generation by the signal generator, and anamplifier to amplify signals generated by the signal generator. The testdevice also includes a controller coupled to communicate with theplurality of generator components.

In one embodiment, the present disclosure provides a method for testinga relay using a relay test device. The method includes generating testsignals to test the relay by a plurality of modular signal generationcomponents of the relay test device. The method includes identifying afailure by one of the plurality of modular signal generation componentsand removing the failed one of the plurality of modular signalgeneration components from within an enclosure of the relay test device.The method provides while the failed one of the modular signalgeneration components is removed from the enclosure of the relay testdevice to generating, by the remaining modular signal generationcomponents, test signals to test the relay. The method includesobtaining a working modular signal generation component and installingthe working modular signal generation component in the enclosure of thetest device. The method also provides for generating, by at least theworking modular signal generation component, test signals to test therelay.

In one embodiment, a system for testing a relay is provided. The systemincludes a signal generator to generate at least one test signal and anamplifier to receive the test signal from the signal generator andamplify the test signal. The amplifier also outputs the test signal tothe relay to test the relay. The system also includes a controllermodule programmable with a relay test procedure. The controller moduleis in communication with the signal generator to promote the signalgenerator generating test signals based on the relay test procedure. Thecontroller module is also operable to monitor a state of the relay andto determine a results of the relay test.

These and other features and advantages will be more clearly understoodfrom the following detailed description taken in conjunction with theaccompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and theadvantages thereof, reference is now made to the following briefdescription, taken in connection with the accompanying drawings anddetailed description, wherein like reference numerals represent likeparts.

FIG. 1 is a block diagram of a relay test device according to oneembodiment.

FIG. 2 is a block diagram of another embodiment of the relay testdevice.

FIG. 3 is a block diagram of a controller module of the relay testdevice.

FIG. 4 is a flow chart illustrating one embodiment of a method for usingthe relay test device.

FIG. 5 is a flow chart illustrating another embodiment of a method forusing the relay test device.

FIG. 6 is a flow chart illustrating another embodiment of a method forusing the relay test device.

FIG. 7 a is a flow chart illustrating another embodiment of a method forusing the relay test device.

FIG. 7 b illustrates another method for employing the relay test deviceaccording to another embodiment.

FIG. 8 is a block diagram of a software and firmware installation systemfor the several embodiments of the relay test device.

FIG. 9 is a flow chart illustrating a method for using a system forinstalling software and/or firmware versions in the relay test device.

FIG. 10 a is a block diagram of one embodiment of a signal generator foruse in the relay test device.

FIG. 10 b is a graph of a constant power output according to anembodiment of the present disclosure.

FIG. 11 is a block diagram of several functional components within thesignal generator of the relay test device.

FIG. 12 is a block diagram of the signal generation functional componentwithin the signal generator of the relay test device.

FIG. 13 is a block diagram of a digital recording playback systememploying an adaptive clock interrupt.

FIG. 14 is a flow chart illustrating a method for using a digitalrecording playback system employing an adaptive clock interrupt.

FIG. 15 is a block diagram of a touch view interface for use with therelay test device.

FIG. 16 depicts one embodiment of a graphical display of the touch viewinterface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It should be understood at the outset that although an exemplaryimplementation of one embodiment of the present disclosure isillustrated below, the present system may be implemented using anynumber of techniques, whether currently known or in existence. Thepresent disclosure should in no way be limited to the exemplaryimplementations, drawings, and techniques illustrated below, includingthe exemplary design and implementation illustrated and describedherein.

Relays may be tested employing a relay test device containing a powerfulpower supply and amplifier and employing a separate personal computer(PC) to control the relay test device. The relay test device may berelatively dumb and may depend upon the separate PC to provide theintelligence needed to test relays. Unfortunately PCs may not operateeffectively in the harsh field conditions where relays are installed.High levels of electromagnetic interference in the field may damage PCsor interfere with the reliable functioning of PCs. Dirt and grit mayreadily infiltrate the mechanical workings of the PC in the field.Industrial use of standard PCs can result in damage to the PC fromexcessive handling, and exposure to environments not well suited forstandard office PC equipment, thereby shortening the lifespan of the PC.

Electrical power distribution transducers, for example, current looptransducers, which provide an indication of the current flowing througha wire or transmission line, are typically tested using an independenttest set operated under the control of the separate PC.

Also, a relay test operator typically must have relatively advancedknowledge of relays and electrical power distribution to test the relaysemploying the relay test device and the separate PC. Personnel withadvanced knowledge may be in limited supply, increasing the electricalpower company's labor cost due to competition to hire limited skilledpersonnel or delaying testing.

In one or more of the disclosed embodiments, the present disclosuredescribes an improved relay test device which combines, in one box, theintelligence necessary to operate independent of the separate PC and tosupport automated tests, integrates in the same box a transducer testingcapability, and includes a number of other new features andcapabilities.

Programmable Relay Test Device

Turning now to FIG. 1, a block diagram of an embodiment of a relay testdevice 10 is depicted. The relay test device 10, includes a controller2, a signal generator module 4 which may include one or more signalgenerators, a plurality of signal amplifiers 6—a first signal amplifier6 a, a second signal amplifier 6 b, and a third signal amplifier 6 c—anda power supply 8. A user interface (UI) 20 is coupled to the controller2 and provides command inputs and displays test results. In the presentembodiment, the controller 2, the signal generator module 4, the signalamplifiers 6, and the power supply 8 may be retained by an enclosure 22.The enclosure 22 may provide shielding from electromagnetic interference(EMI), help control cooling of the system electronics comprised of thecontroller 2, the signal generator module 4, the signal amplifiers 6,the power supply 8 and provide environmental protection. In someembodiments the enclosure 22 may not completely enclose the controller2, the signal generator module 4, the signal amplifiers 6, and the powersupply 8. The enclosure 22 may be open on one or more sides. Theenclosure 22 may be formed of various materials, including metal orpolymeric materials. The enclosure 22 may be formed of expanded metalmaterial. The enclosure 22 may also be referred to as a chassis, anequipment cabinet, a shell, or a body.

A relay under test 24 is depicted as connected to the output of thefirst signal amplifier 6 a. In some test scenarios, the relay under test24 may be connected to the relay test device 10 in other manners, andthe connection between the relay under test 24 and the relay test device10 may include a plurality of wires or cables. Some relays now providean Ethernet interface, and the relay test device 10 may communicate withthe relay under test 24 via an Ethernet connection.

The controller 2, in this embodiment, may include a central processorunit (CPU), which may be composed of one or more digital signalprocessors (DSPs), microprocessors (uPs), microcontrollers (uCs), fieldprogrammable gate arrays (FPGAs), complex programmable logic devices(CPLDs), programmable logic devices (PLDs), and/or application specificintegrated circuits (ASICs). The CPU of the controller 2 may employ anoperating system, such as a Real Time Operating System (hereinafterreferred to as “RTOS”) or a standard non-deterministic operating system.

The controller 2 may contain a plurality of memory devices including oneor more random access memory (RAM), read only memory (ROM), erasableprogrammable read only memory (EPROM), electrically erasableprogrammable read only memory (EEPROM), and Flash memory or acombination thereof. The controller 2 may have multiple interfaces,collectively referred to as input/output (I/O) 7, including but notlimited to any communications method, such as an Ethernet interface, awireless interface, an IEEE-1394 interface, an IEEE-488 interface, aRS-232 interface, a RS-422 interface, a printer interface, a universalserial bus interface (USB), a proprietary intercommunications interface,a plurality of programmable digital inputs, a plurality of programmabledigital outputs, one or more transducer inputs, and other interfaces.These interfaces permit the relay test device 10 to communicate withother devices, for example via an internet, via an intranet, viawireless communications, and via satellite or other means to otherdata-oriented systems, such as a PC or another controller 2 on aseparate system for particular methods of test or data acquisition.

The controller 2 may store, in one or more of the memory devices, suchas memory location 5, a test procedure or test program that thecontroller 2 executes to sequence the relay test device 10 through thesteps of testing the relay under test 24. The controller 2 also maystore, in one or more of the memory devices, a test procedure or testprogram that the controller 2 executes to test a transducer, for exampleto test a current loop transducer using the transducer input. Thecontroller 2 may communicate with the relay under test 24, for examplevia Ethernet, to request from the relay under test 24 information aboutthe settings or control configuration of the relay under test 24 and tocommand or reprogram the relay under test 24 to a group of settings orcontrol configuration sent to the relay under test 24 by the controller2. The controller 2 is in communication with the signal generator module4 and controls the signal generator module 4 to produce desirable testsignals. The controller 2 monitors the relay under test 24 throughoutthe test, determines a result of the test of the relay under test 24,and sends the result to the UI 20 to be displayed.

The controller 2 may log all the results, test procedure actions andstate changes of the relay, including initial settings, commonly termed“as found settings,” of the relay under test 24 and any reprogrammingsettings sent to the relay under test 24, to memory where it may beaccessed at a later time. The access of this data may be accomplishedusing one of the interfaces of the controller 2, for example overEthernet or over wireless or other typical communications means to theInternet, or the relay test device 10 may be transported to alaboratory, office, or shop to download one or more test logs forfurther. analysis. The test logs make it possible to accuratelyreproduce a test run, even if the test system default values arechanged. The relay test device 10 may be in communication with otherequipment employed in testing the relay under test 24, and the relaytest device 10 may store, such as in the system memory, informationprovided by the other equipment.

The signal generator module 4 provides a test signal to each of thesignal amplifiers 6. Each signal amplifier 6 boosts the test signal to alevel which is useful for outputting to test the relay under test 24. Inone embodiment, the signal amplifier 6 may produce a 150 to 200 volt-amp(VA) power level. In other embodiments, the signal amplifier 6 may berated to produce maximum power outputs in the range from only a few VAto several thousand VA, depending on the type and application of theprotection relay being tested. Typically, signal generators used forcommunications and bench top electronic circuit design work provide lowlevel signals, such as 1 to 12 volts into an impedance of 50 to 75 ohms.Signal generators used in protection relay testing typically utilizepower levels greater than this, and, in some embodiments, may be focusedon 50 and 60 Hz line rates, utilizing voltages of 5 volts to 300 voltsinto impedances that vary from less than one-tenth ohm to as much ormore than 600 ohms. In addition, signal generators used in bench topelectronic circuit design are usually not designed to drive a widevariety of loads, such as presented by various protective relayinstruments, nor provide the wide range of voltages and currentsrequired. Protective relay testing may use signal generators that areoriented towards abrupt changes and arbitrary waveform generationmimicking abrupt faults applied to a protection relay, although subtlechanges and constant signals are used in various forms of protectiverelay testing, such as with testing phase-related protection relays andgeneration system protection relays. The power supply 8 provides directcurrent (DC) power to each of the signal amplifiers 6. The power supply8 receives alternating current (AC) power from the AC power mains (notshown) within the relay test device 10. The AC power mains receive powerfrom, for example, a power chord and plug connected to external utilitypower. The controller 2 and the signal generator module 4 may receive DCpower from the power supply 8 or may receive power from one or moreother DC power supplies (not shown).

The signal generator module 4 includes a central processor unit (CPU)which may be composed of one or more DSPs, uPs, uCs, FPGAs, CPLDs, PLDs,and/or ASICs. The signal generator module 4 may include one or morememories including RAM, ROM, EPROM, EEPROM, and Flash memory or acombination thereof. The signal generator module 4 may generate complexsignals from waveform components using a computer program, software, orfirmware stored in one or more memories. The signal generator module 4may playback periodic waveforms stored in data tables, may playback adigital fault recording (DFR) recorded by or of a relay, or may playbacka streaming digital data recording or real-time stream from anothersource such as an external signal data reproduction system such as a PCor data recorder via means similar to MP3 streams utilized on theInternet for audio streaming broadcasts today. These processes arediscussed in more detail hereinafter when discussing another embodimentof the relay test device 10.

The relay test device 10 provides a stand-alone test set which may beused by personnel with relatively limited knowledge and experience ofrelays and electrical power distribution. The relay test device 10 maysimplify the complex field test procedures associated with other testdevices down to procedures involving pointing and clicking by fieldservice personnel which causes complete tests to run and test results tobe reported and stored. In one embodiment, the relay test device 10 maysupport initiating tests from and displaying and analyzing results on ageneral purpose computer system, such as a personal computer or aworkstation, for example in a manufacturer's relay test shop, or via adisplay directly associated and a part of the relay test device 10. Insome embodiments, a relay status monitor feedback 3 is operable tocommunicate with a timer 9.

Turning now to FIG. 2, a block diagram of another embodiment of therelay test device 10 is depicted. While the embodiment of the relay testdevice 10 depicted in FIG. 1 provides many of the same advantages andcapabilities of the embodiment of the relay test device 10 depicted inFIG. 2, the embodiment depicted in FIG. 1 contains a single point offailure in the signal generator module 4 and a single point of failurein the power supply 8. For example, if the signal generator module 4fails, the embodiment of the relay test device 10 depicted in FIG. 1 maybe unavailable for continued testing. Similarly, if the power supply 8fails, the embodiment of the relay test device 10 depicted in FIG. 1cannot continue testing. The embodiment of the relay test device 10depicted in FIG. 2 removes many of the critical single points of failureassociated with the architecture of the relay test device 10 depicted inFIG. 1, by utilizing redundant elements in the areas of the design mostprone to stress induced failures.

The relay test device 10 includes a backplane 12, a controller module14, and a plurality of VI (voltage and current) generators 16—a first VIgenerator 16 a, a second VI generator 16 b, a third VI generator 16 c,and a VI generator 16 d. In an embodiment, the VI generators 16, whichmay also be referred to as signal generators, communicate with thecontroller module 14 over a low voltage differential signaling (LVDS)data bus 18 and employ an error checking and correction protocol toassure reliable communications. The error checking and correctionprotocol may employ parity bits, packet delimiters or markers, packetreceipt confirmation handshakes, cyclic redundancy checking (CRC),and/or other well known methods of verifying communications. In anotherembodiment, however, the LVDS bus may not be employed, and alternativecommunication buses may be employed. In another embodiment the errorchecking and correction protocol is not employed. In some embodiments,either more or fewer VI generators 16 may be installed in the relay testdevice 10.

The controller module 14 may communicate with a user interface (UI) 20via a connector on the backplane 12. In an alternate embodiment, thecontroller module 14 may communicate with the UI 20 without routingthrough the backplane 12. In an embodiment, the UI 20 communicates withthe controller module 14 using LVDS. In the embodiment depicted in FIG.2, the LVDS data bus 18 is shown separately from the backplane, whereasin another embodiment, the LVDS data bus 18 may be integrated within thebackplane. The controller module 14 employs an error checking andcorrection protocol to assure reliable communication with the UI 20. Theerror checking and correction protocol may employ parity bits, packetdelimiters or markers, packet receipt confirmation handshakes, CRC,and/or other well known methods of verifying communications. In anotherembodiment, however, LVDS may not be employed. In another embodiment theerror checking and correction protocol is not employed. The controllermodule 14 receives DC power from a DC power supply (not shown).

The relay under test 24 is depicted as connected to the output of thesecond signal generator 16 b. In some test scenarios, the relay undertest 24 may be connected to the relay test device 10 in other manners,and the connection between the relay under test 24 and the relay testdevice 10 may include a plurality of wires or cables.

The controller module 14 may be referred to as a digital module. Thecontroller module 14 may connect to at least a portion of the I/O 7directly add may connect to other interfaces via the backplane 12. TheVI generators 16 may be referred to as VIGENs, because they may generatevoltage (V) and current (I) signals. In the present embodiment, thebackplane 12, the controller module 14, the VI generators 16, and theLVDS data bus 18 are retained within the enclosure 22. In someembodiments the enclosure 22 may not completely enclose the backplane12, the controller module 14, the VI generators 16, and the LVDS databus 18.

The backplane 12 provides connectivity to receive a plurality of inputsand to transmit a plurality of autonomous outputs. The controller module14 and the VI generators 16 connect to the inputs and outputs, each ofwhich will be discussed hereafter in association with the controllermodule 14 and the VI generators 16.

Turning now to FIG. 3, a block diagram of the controller module 14 isdepicted. The controller module 14 includes an embedded PC CPU 100, atimer CPU 102, and a first LVDS transceiver 104. The embedded PC CPU 100may comprise one or more DSPs, FPGAs, PLDs, CPLDs, ASICs, uPs, uCs, or acombination thereof. The embedded PC CPU 100 is in communication withmemory 105, the LVDS transceiver 104, input/output devices, and networkconnectivity devices. The input/output devices and network connectivitydevices may be collectively referred to as I/O 7. Some of the I/O 7depicted in FIG. 3 may route through the backplane 12 while some of theI/O 7 may directly connect to interfaces or external devices. In anembodiment, the embedded PC CPU 100 may be in communication with asecondary memory device, for example, a magnetic disk storage device, anoptical disk storage device, another type of media storage deviceemploying an alternate media, or a memory device represented as a diskstorage device to the embedded PC CPU 100. Memory devices, such as amemory 105 and a flash disk I/O 103, may be located on the controllermodule 14 and accessible to the embedded PC CPU 100 and the timer CPU102. The memory devices may include such as RAM, ROM, EPROM, EEPROM, andFlash memory or a combination thereof. In an embodiment, the controllermodule 14 is provided with significant memory, such as 64 megabytes ofmemory. The controller module 14 may store test parameters, multipleversions of software and firmware, and multiple versions of an operatingsystem.

In an embodiment, the controller module 14 is a single board computer(SBC). The term SBC is an industry standard term for a self-containedcomputer system. An SBC may contain a CPU (such as an X86, ARM, Risc orother type of main processing unit) memory for random access operationtypically utilized by the operating system and the applications, storageof data such as disk on a chip (DOC) compact flash, or microdrive, aswell as standard interfaces such as IDE to connect to the compact flash,microdrive or standard externally mounted drive you see in a standarddesk top PC. It usually also contains standard interfaces, such asRS-232, Digital I/O, PC104 and PC104 Plus interfaces, and often containsUSB, Ethernet, keyboard, mouse and video display interface capabilities.

The input/output devices may include one or more RS-232 serial dataports, RS-422 serial data ports, IEEE-488 ports, printer interfaces, USBinterfaces, Ethernet ports, and EPOCH high current interface ports. Someof these input/output devices may be connected as I/O 7 directly to thePC CPU 100. The input/output devices may also include one or more clockinputs, clock outputs, transducer inputs, touch view interfaces, aplurality of programmable digital inputs, and a plurality ofprogrammable digital outputs. In an embodiment, the programmable I/O 107may be connected to the timer CPU 102. These interfaces permit the relaytest device 10 to communicate with other devices, for example via anInternet, via an intranet, via wireless communications, and viasatellite. In an embodiment, the embedded PC CPU 100 employs theVxWorks® operating system.

The embedded PC CPU 100 executes software or firmware operable toinstall versions of software and of firmware, to manage the UI 20, toreceive and store a definition of a test procedure, and to manage allthe resources of the relay test device 10 during testing activities. Theembedded PC CPU 100 executes programs that test the relay under test 24.The embedded PC CPU 100 also executes programs that test transducers,for example current transducers. The relay test device 10 may store aplurality of user profiles, for example in the memory on the controllermodule 14. The user profiles include individual user preferences and mayinclude user specific cues, such as reminders of in-progress activitiesor things to do. User preferences may include display preferences, forexample displaying vectors in the range from −180 degrees to +180degrees versus displaying vectors in the range from 0 degrees to 360degrees. The user profile may be stored with test data so that the testof the relay under test 24 may be completely re-created.

The UI 20 is a ruggedized input/output device based on a video display,touch screen and controller, and a CPLD for communications with theembedded PC CPU 100, a user control dial and enclosure. In the preferredembodiment, the embedded PC CPU 100 provides the intelligence andprocessing capabilities for the UI 20. As such, the embedded PC CPU 100determines the content of the display to be presented by the UI 20 andsends the content of the display to the UI 20. The UI 20 receives acontrol input and sends user initiated control input to the embedded PCCPU 100. The embedded PC CPU 100 processes the control input from the UI20, including navigating through a hierarchy of displays. In analternate embodiment, however, the UI 20 may provide the intelligenceand processing power to navigate through menus and to generate thecontent of the display. In an alternate embodiment the UI 20 may containand execute test procedures and send test control commands to the VIgenerators 16 via the controller module 14 or via another communicationpath. A touch view interface (TVI), a particular embodiment of the UI20, will be discussed in greater detail hereinafter.

The embedded PC CPU 100 may receive the definitions of test proceduresthrough a network connection, for example an Ethernet connection to alocal area network (LAN), and stores the definitions of test proceduresin memory, such as in RAM or in nonvolatile memory such as flash memory.The relay test device 10 may receive definitions of test procedures inan office LAN environment, for example. Alternately, the relay testdevice 10 may receive definitions of test procedures in the field, forexample via an Ethernet connection to a laptop PC having wirelessconnectivity to an Internet or to a mobile phone having wirelessconnectivity to an Internet. In an embodiment, the embedded PC CPU 100may receive the definitions of test procedures through a differentconnection, such as through a serial interface or an USB interface.Numerous other means of receiving definitions of test procedures viavarious Interfaces are within the scope of the present disclosure andwill readily suggest themselves to one skilled in the art.

The embedded PC CPU 100 may control the execution of test sequences byexecuting a generic test loop, customized by reading or analyzing thedefinition of a test procedure stored in the controller module 14. Testsequence operations may include sending data files to the VI generators16, configuring the VI generators 16, responding to the programmabledigital inputs, and driving the programmable digital outputs. Testsequence operations may include interrogating the relay under test 24 todetermine the initial or “as found” settings of the relay under test 24,storing the as found settings of the relay under test 24, changing thesettings of the relay under test 24. Test sequences may also includetesting the relay under test 24, determining the status of the relayunder test 24, furthermore determining the success or failure of thetest of the relay under test 24, and restoring the as found settingsinto the relay under test 24. The test sequence operations may includechanging the settings of the relay under test 24 to factory settings asa precondition for running the test.

The embedded PC CPU 100 generates a log of the execution of testsequences and of inputs, for example the programmable inputs from thetimer CPU 102. The test sequence operations may include interrogating arelay to determine the settings of the relay under test 24, testing therelay according to a specific or generic test procedure which iscustomized by using the settings of the relay under test 24—this may betermed testing the relay under test 24 according to its settings or “asfound” settings—and determining success or failure of the test.

The embedded PC CPU 100 may log the actions of the test sequences, theinputs, and the state changes of the relay under test 24 to memory 105.Thereafter, one or more test logs may be downloaded over one of theinterfaces of the controller module 14. Alternately, the relay testdevice 10 may be transported to a laboratory, office, or shop todownload one or more test logs for further analysis. The test logs maybe printed out by a printer connected to the printer interface or to theUSB interface. The test logs make it possible to accurately reproduce atest run, even if the test system default values are changed. The relaytest device 10 may be in communication with other equipment employed intesting the relay under test 24, and the relay test device 10 may storein the test logs information provided by the other equipment.

Turning now to FIG. 4, a method for using the relay test device 10 isdepicted. At block 200 a test procedure is received and stored in therelay test device 10. The test procedure may have been defined orprogrammed by personnel skilled with protection relay systems andequipment and/or electrical power distribution technology andregulations. The test procedure describes a series of actions for therelay test device 10 to take to test the relay under test 24. The testprocedure may include data, such as a DFR or a data table representing aperiodic waveform. Alternately, data may be received by the relay testdevice 10 in a separate step after or before block 200. In anembodiment, the test procedure may be expressed in an advanced visualtest software (AVTS) proprietary programming language. Single AVTScommands are expanded into several relay test system (RTS) commands,where RTS is another proprietary programming language. Single RTScommands are expanded into several commands to the VI generator 16executable by the VI CPU 450 depicted in FIG. 10 a. The commands to theVI generator 16 may be, for example, assembly language commands in thenative language of the DSP 464. In another embodiment, the commands tothe VI generator 16 may be based on a proprietary language schemeoptimized for reducing data volume on the LVDS data bus 18, promotingtest signal generation by desired characteristics of a test signal, suchas relative phase to other VI generators 16, reference to an internal orexternal clocking source, change of frequency, change of amplitude, DCoffset or voltage offset, start and stop control of the signals.

In an embodiment, the relay test device 10 may receive the testprocedure or test procedure updates through communication with externaldevices, for example through Ethernet communication with a laptopcomputer. The test procedure may be downloaded to the relay test device10 from a laptop computer in a lab, office, or shop, and the relay testdevice 10 may be transported thereafter to the field to test relays. Inanother embodiment, the relay test device may be temporarily resident ata remote location, such as an electrical substation location, andreceive the test procedure updates downloaded through the Wide AreaNetwork (WAN) from a PC or intranet or Internet or other type of filetransfer capable data storage and retrieval site. In another embodiment,the relay test device 10 may receive the test procedure originating froma memory device such as a flash memory card integral to the embedded PCCPU 100, an optical disk inserted into an optical disk reader, amagnetic disk inserted into a magnetic disk reader, or an alternatemedia inserted into an alternate media storage device which may beintegral to the relay test device 10.

The method proceeds to block 202 where the relay test device 10 isconnected to the relay under test 24, the test procedure is started orinitiated, and the relay test device 10 performs an action of the testprocedure. A field operator without special knowledge of relays orelectrical power distribution technology or regulations may transportthe relay test device 10 to the field, connect the relay test device 10to the relay under test, and initiate the test procedure. In anembodiment, the UI 20 may provide a depiction of a schematic drawing ora bit map digital image of, for example, a relay and patch cablesconnecting to the relay which facilitates connecting the relay undertest 24 to the relay test device 10. The embedded PC CPU 100 may read aninstruction of a computer program encoding the test procedure and, basedon this instruction, command one or more VI generators 16 to output atest signal to the relay under test 24. Alternately, the embedded PC CPU100 may command the timer CPU 102 to output a state on one of theprogrammed outputs. The VI generator 16 outputs a test signal to therelay under test 24 and/or the timer CPU 102 outputs a state on one ofthe programmed outputs to the relay under test 24.

The method proceeds to block 204 where the relay test device 10 monitorsthe relay under test 24. The relay test device 10 may monitor aplurality of indications of a state of the relay under test 24. In someembodiments, the relay test device 10 generates a log of the testactions and the indications of the state of the relay under test 24. Themethod proceeds to block 206 where the method returns to block 202 ifthe test of the relay under test 24 is incomplete. By looping throughblock 202 and block 204 the relay test device 10 sequences through thetest procedure and tests the relay under test 24. In some testprocedures, the relay test device 10 may generate a voltage or currentsignal which the relay test device 10 sends to the relay under test 24,such as the voltage and current signals which the VI generators 16 arecapable of generating.

When the test of the relay under test 24 is complete, the methodproceeds to block 208 where the relay test device 10 analyzes the finalstate of the relay under test 24 to determine whether the relay undertest 24 passed or failed the test. The method proceeds to block 210where the relay test device 10 reports the test result to the UI 20. Inan embodiment, the log of the test actions and the indications of therelay may be stored in a file in memory 105 or memory storage device103, and the file may be transferred to an external device, for exampleto a laptop computer via Ethernet communications. The log may beanalyzed in more detail at a later time, for example in a corporateoffice or laboratory for the purpose of verifying pass or fail testresults.

Turning now to FIG. 5, a method for using the relay test device 10according to another embodiment is depicted. The method depicted in FIG.5 is substantially the same as the method depicted in FIG. 4, withdifferences noted below. It is understood that after block 250 andbefore block 252 a field operator without special knowledge of relays orelectrical power distribution technology or regulations may transportthe relay test device 10 to the field, connect the relay test device 10to the relay under test 24, and initiate the test procedure. At block252 the relay test device 10 reads the initial settings, initialconfiguration parameters, or initial adjustments of the relay under test24 from the relay under test 24. The relay test device 10 stores theinitial settings otherwise known as “as found” data of the relay undertest 24.

The method proceeds to block 254 where the relay test device 10 writestest settings to the relay under test 24. This action may be referred toas reprogramming the relay under test 24. In some cases, the testsettings may be factory settings specified for the relay under test 24,or special test settings which ensure specific relay elements operate asexpected, without influence from other relay test device 10 elements notof interest for the specific test applied. The method loops throughblocks 256, 258, and 260 performing the test of the relay under test 24.At block 262 the relay test device 10 analyzes the final state of therelay under test 24 to determine whether the relay under test 24 passedor failed the test. The method proceeds to block 266 where the relaytest device 10 writes the initial settings to the relay under test 24,to restore the relay under test 24 to its initial condition. The methodproceeds to block 266 where the relay test device 10 reports the testresult to the user interface 20.

Turning now to FIG. 6, another method for using the relay test device 10is depicted. The method depicted in FIG. 6 is substantially the same asthe method depicted in FIG. 5 with differences noted below. It isunderstood that after block 300 and before block 302 a field operatorwithout special knowledge of relays or electrical power distributiontechnology or regulations may transport the relay test device 10 to thefield, connect the relay test device 10 to the relay under test 24, andinitiate the test procedure. After testing the relay under test 24according to a first group of relay settings, the method proceeds toblock 312 where the relay test device 10 analyzes the state of the relayunder test 24 to determine whether the relay under test 24 passed orfailed the test according to the particular group of relay settings. Themethod proceeds to block 314 where the method returns to block 304 ifthe relay under test 24 has not been tested according to all groups ofrelay settings which the test procedure calls for testing. By loopingthrough blocks 304, 306, 308, 310, and 312 the relay under test 24 istested according to each of several test relay settings. At block 314 ifthe test of the relay under test 24 is complete, the method proceeds toblock 316 where the relay test device 10 writes the initial relaysettings to the relay under test 24, to restore the relay under test 24to its initial condition. The method proceeds to block 318 where therelay test device 10 reports the test results to the UI 20.

Turning now to FIG. 7 a, another method for using the relay test device10 is depicted. The method depicted in FIG. 7 a is substantially thesame as the method depicted in FIG. 4 with differences noted below. Itis understood that after block 324 and before block 326 a field operatorwithout special knowledge of relays or electrical power distributiontechnology or regulations may transport the relay test device 10 to thefield, connect the relay test device 10 to the relay under test 24, andinitiate the test procedure. At block 326 the relay test device 10 readsthe as found relay settings. The method proceeds to block 328 where thetest relay device 10 performs an action of the test procedure based onthe as found relay settings which were read in. This step corresponds totesting the relay under test 24 according to its as found settings, andif a relay having different settings from another relay is tested usingthe same test procedure stored in the relay test device 10, the testactions will differ accordingly.

Turning now to FIG. 7 b, another method for using the relay test device10 is depicted. The method depicted in FIG. 7 b is substantially thesame as the method depicted in FIG. 4 with differences noted below. Itis understood that after block 354 and before block 356 a field operatorwithout special knowledge of relays or electrical power distributiontechnology or regulations may transport the relay test device 10 to thefield, connect the relay test device 10 to the relay under test 24, andinitiate the test procedure. At block 354 the procedure step containsboth a test procedure and a new desired characteristic behavior of therelay under test 24 based on settings to be determined by test. At block356 the relay test device 10 reads the initial relay settings.

The method proceeds to block 358 where the test relay device 10 performsan action of the test procedure based on the as found relay settingswhich were read in. The method proceeds to block 360 where if the relayunder test 24 passes the test with expected results, the relay can thenbe re-programmed with new settings which may cause the relay under test24 to exhibit the desired characteristic stored in block 354. Assumingthe results of the testing at block 358 were successful, the methodproceeds to block 362.

In block 362 a search algorithm determines relay settings that may leadthe relay under test 24 to exhibit the desired characteristic whentested. The search algorithm may be designed to approach the settingsthat produce the desired characteristic by determining a succession ofmaximum and minimum settings and refining the maximum and minimumsettings each iteration through the test loop. Alternately, anotheralgorithm for finding relay settings suitable for testing the relayunder test 24 may be employed. The relay under test 24 is reprogrammedwith the determined relay settings utilizing Ethernet, RS-232 or othercommunications means used by industry standard relays.

The method proceeds to block 364 where the relay under test 24 is testedaccording to the settings. The method proceeds to block 366 where if therelay under test 24 exhibited the desired characteristic the test issuccessful and the method exits. If the relay under test 24 did notexhibit the desired characteristic, the method proceeds to block 368. Inblock 368 if the characteristic is determined to be unachievable, forexample if a maximum number of test iterations have completed withoutachieving the desired characteristic, the method exits otherwise themethod returns to block 362. By looping through blocks 362, 364, 366,and 368 the relay under test 24 is tested according to a number ofsettings to find if the desired characteristic can be achieved.

The settings required and actual characteristics of the relay under test24 are logged into memory or sent via network communications to a datastorage system, such as a PC or web server for analysis by personnelskilled in the art of protective relay settings, application andtesting.

The relay test device 10 provides a stand-alone test set which may beused by personnel with relatively limited knowledge and experience ofrelays and electrical power distribution. The relay test device 10 maysimplify the complex field test procedures associated with other testdevices down to procedures involving pointing and clicking by fieldservice personnel which causes complete tests to run and test results tobe reported. In an embodiment, the relay test device 10 may supportinitiating tests from and displaying and analyzing results on a generalpurpose computer system, such as a personal computer or a workstation,for example in a manufacturer's relay test shop. In another embodimentthe relay test device 10 may utilize network communications, such asEthernet, Internet, intranet or wireless networks, to support initiatingtests from and displaying results on a general purpose computer system,such as a personal computer or workstation while the relay test device10 is located remotely from the general purpose computer system, such asrelay test device 10 located at an electrical distribution substationhundreds or thousands of miles away from the general purpose personalcomputer located at a main service office where skilled personnel may beconsolidated to reduce costs, utilizing less expensive field personnelfor traveling from site to site and connecting relay test device 10 torelays under test 24. Software loaded on a personal computer,workstation, or the relay test device 10 may be used to create, analyze,and perform relay tests.

Software and Firmware Installation System for a Relay Test Device

Installing versions of software and firmware into the relay test device10 may involve changing the stored instructions associated with DSPs,PLDs, ASICs, uPs, and uCs inside the relay test device 10 and in the UI20. The versions of software and firmware may be updates, functionalcorrections, revisions, prior versions, and/or new versions. Theversions of software may include test procedures. All of these softwareand firmware changes or installations are contemplated by the use of theterm version or installation. Installing versions of software andfirmware may entail installing the versions into memory in a specificorder. In one embodiment, the relay test device 10 may initiate contactwith a remote computer system in the event of a failure or for upgradingor updating. Communication could also be initiated by the remotecomputer system, such as a support computer maintained by the devicevendor. Either or both the remote computer system or relay test device10 may perform a diagnostic analysis of the relay test device 10 todetermine the versions or levels of the firmware on the relay testdevice 10. Diagnostic information may include a serial number or otheridentifier for the relay test device 10, serial numbers or identifiersfor each of the programmable modules and programming instructions orfirmware levels currently on the relay test device 10. These identifiersmay be communicated in a file and/or stored on the relay test device 10and/or the remote computer system. In the event a new module, updatedinstruction, or firmware level is loaded onto the relay test device 10to fix a particular problem, for example, a complete update to allsystems within the relay test device 10 may be warranted based on ananalysis of the diagnostics of other firmware levels. Also, the remotecomputer system may maintain a list of the relay test devices 10 whoseowners pay for technical support and updates may only be provided basedon support agreements. The relay test device 10 may provide users anotice where an update is unavailable because no technical supportagreement with the vendor is in place.

Because many of the behaviors of the relay test device 10 are commandedor determined by software and firmware, installing versions of softwareand firmware can change the basic function of the relay test device 10,including changing the basic function to perform tests of devices otherthan electrical power protection relays. For example, the relay testdevice 10 may be reprogrammed to test stepper motors, solenoids,hydraulic pumps, and other devices requiring a powerful voltage and/orcurrent signal to be tested. The embedded PC CPU 100 may receive theversions of software and firmware through network connections, forexample an Ethernet connection to a LAN, and stores the versions ofsoftware and firmware.

Turning now to FIG. 8, an embodiment of a software and firmwareinstallation system for the relay test device 10 is depicted. The relaytest device 10 includes an installation control component 420 incommunication with a plurality of CPUs 422—a first CPU 422 a and asecond CPU 422 b. The installation control component 420 and the CPUs422 may comprise one or more DSPs, FPGAs, PLDs, CPLDs, ASICs, uPs, anduCs. Each of the CPUs 422 are associated with an installation routine424—the first CPU 422 a is associated with a first installation routine424 a and the second CPU 422 b is associated with a second installationroutine 424 b. The control module 420 is associated with a thirdinstallation routine 424 c. Each of the CPUs 422 and the installationcontrol component 420 execute software or firmware, which may bereferred to as programs, out of one or more program memory 426 toaccomplish their basic functions, for example testing a relay under test24.

The program memory 426 may be non-volatile memory including EPROM,EEPROM, Flash, and/or other non-volatile reprogrammable memory. Theprogram memory 426 may have precise real-time programming requirements.For example, an EEPROM may need to have a particular sequence of binarywords written to it to disable a write-protected mode and then theEEPROM may need to be written to at least every 3 mS or the EEPROM mayrevert to write-protected mode. It is understood that this programmingprotocol is only exemplary and that other programming protocols mayapply to other program memory 426. The first CPU 422 a is associatedwith a first program memory 426 a-1, a second program memory 426 a-2,and a third program memory 426 a-3. The second CPU 422 b is associatedwith a fourth program memory 426 b-1, a fifth program memory 426 b-2,and a sixth program memory 426 b-3. The control component 420 isassociated with a seventh program memory 426 c. The programs stored inthe program memory 426 provide much of the functionality of the relaytest device 10. The installation routines 424 contain instructions forinstalling versions of software or firmware into the one or more programmemory 426.

In one embodiment a version oracle file may be provided which describesthe versioned programs 428 that are available, the interdependenciesthat exists among the versioned programs 428, the installation sequencethat is mandatory for particular combinations of versioned programs 428,and other information pertinent to installing versioned programs 428.The third installation routine 424 c may download the version oraclefile from an FTP site, process the version oracle file, and perform aninstallation of versioned programs 428 based on processing the versionoracle file.

A plurality of versioned programs 428—a first versioned program 428 a, asecond versioned program 428 a-2, a third versioned program 428 a-3, afourth versioned program 428 b-1, a fifth versioned program 428 b-2, asixth versioned program 428 b-3, and a seventh versioned program 428c—may be provided to the installation control component 420 orstored/saved elsewhere. The versioned programs 428 may be versions ofthe programs stored in the program memory 426. The installation controlcomponent 420 may receive the versioned programs 428 throughcommunications, for example through Ethernet communication with a laptopcomputer or using the file transfer protocol (FTP) to access a FTPstorage site via the Internet. The installation control component 420may receive the versioned programs 428 through communication such as,but not limited to, with an optical disk reader, with a magnetic diskreader, or with another media storage device using an alternate mediawhich is part of the relay test device 10.

The installation control component 420 is operable to install theversioned programs 428 by communicating the versioned programs 428 tothe appropriate CPUs 422 and by causing the installation routines 424 tobe executed, installing the versioned programs 428 into the appropriateprogram memory 426. This process may include executing the firstinstallation routine 424 a to install the versioned programs 428 a-1,428 a-2, and 428 a-3 into program memory 426 a-1, 426 a-2, and 426 a-3associated with the first CPU 422 a. This process may include executingthe second installation routine 424 b to install the versioned programs428 b-1, 428 b-2, and 428 b-3 into the program memory 426 b-1, 426 b-2,and 426 b-3 associated with the second CPU 422 b. This process mayinclude executing the third installation routine 424 c to install theseventh versioned program 428 c into the seventh program memory 426 cassociated with the control module 420.

The first installation routine 424 a and the second installation routine424 b may be required to meet the precise programming protocolsassociated with the program memory 426. In an embodiment where tightprogramming timing protocols may not be associated with the programmemory 426, the third installation routine 426 c may directly controlthe installation of versioned programs 428 a-1, 428 a-2, and 428 a-3 onthe program memory 426 a-1, 426 a-2, and 426 a-3 and the installation ofversioned programs 428 b-1, 428 b-2, and 428 b-3 on the program memory426 b-1, 426 b-2, and 426 b-3. In this embodiment, there may be no needof the first installation routine 424 a and the second installationroutine 424 b.

Furthermore, additional programmable devices 422, for example an FPGA422 c and a CPLD 422 d, may be in indirect communication with theinstallation control component 420. The exemplary FPGA 422 c is incommunication with the first CPU 422 a and indirectly with theinstallation control component 420 via the first CPU 422 a. Theexemplary CPLD 422 d is in communication with the FPGA 422 c andindirectly in communication with the first CPU 422 a via the FPGA 422 c.In an embodiment, it may be desirable to install the versioned program428 into the CPLD 422 d before installing the versioned program 428 intothe FPGA 422 c. If a new communication mechanism is deployed in theversioned programs 428, the CPLD 422 d and the FPGA 422 c may not beable to communicate when they execute according to incompatibleversioned programs 428. If the CPLD 422 d is updated first, the FPGA 422c may not be able to communicate with the CPLD 422 d, but the FPGA 422 cmay still be able to be updated. If the FPGA 422 c is updated first, theFPGA 422 c may not be able to communicate with the CPLD 422 d and hencethe CPLD 422 d may be isolated and incapable of being updated. The CPLD422 d and the FPGA 422 c may be updated by the first installationroutine 424 a associated with the first CPU 422 a. In an alternateembodiment, the CPLD 422 d and the FPGA 422 c may be associated withtheir own installation routines 424, not shown, and may execute theirown installation routines to effect the installation of the versionedprogram 428.

When the operating system executes out of RAM, the third installationroutine 424 c may install a version of the operating system into theprogram memory 426 associated with the embedded PC CPU 100, and when theembedded PC CPU 100 reboots, the version of the operating systemrecently installed is executed.

The software and firmware installation system for the relay test device10 may be employed to support delivery of test procedures to customers.For example, a test procedure for a newly released relay may bedeveloped by the manufacturer of the relay test device 10. Themanufacturer may provide the software encoding that includes the newtest procedure to customers who own the relay test device 10. Thecustomer, having acquired access to the software encoding of the newtest procedure may download the software encoding from a FTP site wherethe manufacturer stores the software encoding of the new test procedureand install the software into the relay test device 10. The downloadingand installation may be conducted employing the software and firmwareinstallation system described above.

In another embodiment, the software and firmware installation system forthe relay test device 10 may be employed to support delivery of testprocedures to customers of the relay under test 24. For example, a testprocedure for a newly released relay may be developed by themanufacturer of the relay under test 24. The manufacturer of the relayunder test 24 may provide the software encoding that includes the newtest procedure to customers who own the relay test device 10. Thecustomer, having acquired access to the software encoding of the newtest procedure may download the software encoding from a FTP site wherethe manufacturer of the relay under test 24 stores the software encodingof the new test procedure and install the software into the relay testdevice 10. The downloading and installation may be conducted employingthe software and firmware installation system described above.

Once downloaded from the FTP site and installed in this manner, thecustomer derives value from the software by testing the relay under test24 using the software. It may be more efficient for the manufacturer ofthe relay test device 10 to develop software encoding relay testprocedures once and sell or provide this software to, for example, fivepower distribution operating companies, than for each of the five powerdistribution operating companies to develop their own software encodingrelay test procedures for the relay test device 10.

The software and firmware installation system for the relay test device10 may be employed to support delivery of bug fixes using a simple pointand click interface, such as a touch screen or standard monitor andmouse found on many PCs. The third installation routine 424 c mayrespond to the activation of a bug fix selection by first downloadingthe version oracle file discussed above and use the version oracle fileto determine what versioned programs 428 to download from the FTP siteand how to install these versioned programs 428.

The basic function of the relay test device 10 may be changed byinstalling versioned programs 428. For example, by installing versionedprograms 428 the relay test device 10 could be reprogrammed to test amotor bank. Versioned programs 428 including a test procedure and/or acomputer program may be installed that control spinning up three motorsfrom 0 revolutions per minute (RPM) to 400 RPM over ten minutes whilethe three motors run synchronously and differ from each other by no morethan one revolution over the entire test run. The motors may providetachometer signals to the programmed inputs of the relay test device 10and forwarded to the three VI generators 16 a, 16 b, and 16 c.

The three VI generators 16 a, 16 b, and 16 c may be reprogrammed byinstalling a versioned program 428 to use the tachometer signals togenerate voltage and/or current output signals to drive the motors. Thisis an exemplary scenario of reprogramming the relay test device 10 toperform activities other than relay testing. Other alternate employmentsfor the relay test device 10 are also contemplated by the presentdisclosure, including for example, but not limited to, using the relaytest device 10 to control and/or test stepper motors, solenoids,hydraulic pumps, and submersible pump motors.

Turning now to FIG. 9, a method of installing software and firmware intothe relay test device 10 is depicted. In block 434 one or more versionedprograms 428 for one or more CPUs 422 are transmitted to the relay testdevice 10. The CPUs 422 may be DSPs, CPLDs, FPGAs, uPs, microcontrollers(uC), and/or ASICs. The versioned programs 428 may be software versionsor firmware versions. The versioned programs 428 may be selected basedon information obtained from a version oracle file described above whichhas been downloaded from an FTP site or based on information provided byanother means. The method proceeds to block 436 where one of theversioned programs 428 is selected for installation in program memory426. In an embodiment, it may be prudent to follow a particular sequencefor installing the versioned programs 428, Installing versioned programs428 into the program memory 426 at the end of communications pathsfirst, installing versioned programs 428 into the program memory 426 inthe middle of communications paths next, and so on, in order to avoidisolating one of the CPUs 422 which is unable to communicate with anyother CPU 422 and hence cannot install the versioned programs 428associated with that isolated CPU 422. The appropriate sequence forinstalling versioned programs 428 may be specified by the version oraclefile or by another means.

The method proceeds to block 438 where one of the versioned programs 428is transmitted to the selected CPU 422. The method proceeds to block 440where the selected CPU 422 executes an installation routine 424. In anembodiment, the selected CPU 422 writes the versioned program 428 to theprogram memory 426, such as a rewriteable static memory device, such asan electrically erasable programmable read only memory (EEPROM), a flashmemory, or other rewriteable static memory device.

The method proceeds to block 442 where if all the versioned programs 428have not been installed the method returns to block 436. By loopingthrough blocks 436, 438, 440, and 442 each of the versioned programs 428is successively installed. When all versioned programs 428 have beeninstalled, the method exits. Note that an installation control component420 may execute an installation routine 424 for installing versionedprograms 428 on other CPUs 422 and install versioned programs 428 onitself as the last action of the installation. For example, thecontroller module 14 may install versioned programs 428 in each of theVI generators 16 and as the last step of a revision procedure installversioned programs 428 associated with the controller module 14.

Returning to FIG. 3, the timer CPU 102 may comprise one or more DSPs,FPGAs, PLDs, CPLDs, ASICs, uPs, uCs, or a combination thereof. The timerCPU 102 is in communication with one or more memory devices, theprogrammable digital inputs, the programmable digital outputs, and thePC CPU 100. The memory devices may include RAM, ROM, EPROM, EEPROM, andFlash memory devices. The programmable digital inputs and outputsprovide timing and logic operations in real-time coordinated with aplurality of outputs of the VI generators 16. The programmable digitalinputs may monitor the operation of relay contacts of the relay undertest 24 or monitor voltages applied, removed or changed, as expected ordesigned in a power distribution protection system test environment.

The programmable digital outputs may simulate adjacent relay logic, orother contact closure events normally found in a power distributionprotection system to the relay under test 24. The programmable digitaloutputs may be used to test circuit breaker event schemes, such asground faults or multiple relay contact closures associated withreclosing relays. The programmable inputs and outputs may be programmed,using Boolean logic, for more complex power system simulations,including vector directed test sequences based on logical AND, OR, NOT,TRUE and FALSE operations, and combinations thereof. For example, theBoolean Logic may be programmed to wait for an event such as “AND” ontwo or more of the input monitoring posts. The logic will determine ifan event on monitoring post input one and monitoring post input two areboth TRUE, then the logic result is TRUE and the condition is satisfiedto proceed to the next step in the program. Another example may includea Boolean Logic case statement controlling an output which may beconditionally determined by the states of the inputs, time, and step ina procedure or program. For example: If input 1=TRUE AND input 2=TRUE ORinput 1=TRUE and input 3=FALSE AND procedure step=17 Output contact3=FALSE, Output contact 1=TRUE. This Boolean logic capability providesthe increased flexibility and complexity of test, such as operationbased on conditions that may change during the course of application ortesting.

Electric power generation facilities and electrical power distributionsubstations are examples of the environments where the relay test device10 may be employed. These environments may have high levels ofelectromagnetic interference (EMI). High EMI levels can cause unreliablecommunication between physically separated electronic devices and evenbetween electronic components located within the same enclosure. HighEMI levels may be particularly problematic when high data communicationrates are used, as they are between the embedded PC CPU 100 and the UI20 and between the PC CPU 100 and the VI generators 16.

LVDS signaling provides a standards-based approach to providing reliablecommunication in a noisy environment. The basic principle of operationof LVDS is to send a binary signal as the difference between voltagelevels on two signal lines rather than as the voltage on a single signalline referenced to a chassis ground. If EMI or noise interferes with thetwo signal lines, both lines should be equally perturbed and in the samesense. For example, if line 1 has a voltage of 1 volt, line 2 has avoltage of −1 volt, and both lines are temporarily interfered with toraise their voltage 2 volts to 3 volts on line 1 and 1 volt on line 2,the voltage difference between line 1 and line 2 remains unchanged, andthe differential signal remains correct. If a single logic line 3 has avoltage of 0.2 volts, and this single logic line 3 is interfered with toraise its voltage 2 volts to 2.2 volts, this may be deemed to havechanged the logic level of the signal, referenced to chassis ground,from a logic 0 or low logic to a logic 1 or high logic, thus corruptingthe signal. Other approaches to providing reliable communications in ahigh EMI environment are also contemplated including using shieldedmedia, optical communication, spread spectrum wireless communication,orthogonal frequency division multiplexing (OFDM), wirelesscommunication, higher voltage level communications, increasing thesignal to noise ratio produced using voltage translators, and infraredcommunication.

Modular Signal Generator, including Real-time Signal and WaveformGeneration

Turning now to FIG. 10 a, a block diagram of the VI generator 16 isdepicted. In this embodiment, the VI generator 16 includes a VI CPU 450,two amplifiers 452—a first amplifier 452 a and a second amplifier 452b—two feedback components 454—a first feedback component 454 a and asecond feedback component 454 b—a VI power supply 456, and a second LVDStransceiver 458. Each amplifier 452 is associated with an output 466—afirst output 466 a associated with the first amplifier 452 a and asecond output 466 b associated with the second amplifier 452 b. Externalinputs 468 a and 468 b are available for feeding signals to one of theamplifiers 452 a and 452 b, respectively.

The external input 468 may be optional because an input to the amplifier452 may be sourced by the VI CPU 450 or, optionally, by the externalinput 468 which is supplied by an external signal, such as an analogsignal played back on a recorder device. The input 468 may be routed tothe VI generator 16 from the backplane 12. Alternately, the input 468may route directly to the VI generator 16. In an embodiment, a digitalto analog converter (DAC) (not shown) may be provided between the VI CPU450 and the amplifier 452 in another embodiment, the DAC may beintegrated with the amplifier 452. While the preferred embodiment of theVI generator 16 provides two amplifiers 452, two feedback components454, and two outputs 466, in other embodiments there may be more orfewer amplifiers 452, feedback components 454, and outputs 466.

The VI generator 16 is a modular component. VI generators 16 areinterchangeable, and, for example, if the first VI generator 16 a fails,the controller module 14 may configure the fourth VI generator 16 d toprovide the same or similar functions that the first VI generator 16 awas providing when the first VI generator 16 a failed. The ability ofthe relay test device 10 to experience a failure of one VI generator 16,for example the first VI generator 16 a, and to continue field testing,as for example by reconfiguring the test procedure to employ the fourthVI generator 16 d in the place of the first VI generator 16 a, providessignificant utility.

The modularity of the VI generator 16 supports a maintenance concept ofremoving a failed VI generator 16, which may be implemented as a circuitboard or circuit card, for example, and sending the failed VI generator16 back to the manufacturer for repair. Meanwhile the relay test device10 may continue to be used in the field or in the shop testing the relayunder test 24 using the remaining generators 16 that are operational.The VI generators 16 may be considered modular based on its unitary orself-contained nature, or based on the ease with which each one of theVI generators 16 may, in one embodiment, be easily coupled and uncoupledfrom the relay test device 10.

This maintenance concept supports a customer purchasing a spare VIgenerator 16 and keeping it in reserve to replace a failed VI generator16. In the case that a customer owns multiple relay test devices 10, thecustomer may purchase less than one spare VI generator 16 per relay testdevice 10 to keep in reserve, based on a calculation of a mean timebetween failures and a mean time to repair for the VI generator 16, asis well known to those skilled in the logistics support art. Forexample, a customer owning ten relay test devices 10 may calculate thatpurchasing three spare VI generators 16 reduces their risk over one yearof any relay test device 10 having to operate with less than a fullcomplement of signal generators to less than 5%. This scenario isexemplary. The redundant VI generator 16 also allows the customer theoption to wait until the repaired or new VI generator 16 is receivedfrom the manufacturer.

The VI CPU 450 may comprise one or more DSPs, FPGAs, PLDs, CPLDs, ASICs,uPs, uCs, or a combination thereof. The software and/or firmware may beinstalled in the VI CPU 450 according to the installation systemdescribed above and referencing FIG. 4. In an embodiment, the VI CPU 450comprises a CPLD 460, a FPGA 462, and a DSP 464. Placing a dedicatedprocessor, the VI CPU 450, on each VI generator 16 permits one VIgenerator 16 to fail, for example the first VI generator 16 a, while theother VI generators 16, for example the second VI generator 16 b, thethird VI generator 16 c, and the fourth VI generator 16 d, continue tooperate normally. Placing a dedicated processor, the VI CPU 450, on eachVI generator 16 permits generation of output signals from complexreal-time calculations, which provides functional flexibility to therelay test device 10. Generation of output signals is discussed ingreater detail hereinafter.

The VI CPU 450 is coupled to memory devices, such as a VI memory 465,which may include ROM, RAM, EPROM, EEPROM, and flash memories. The VICPU 450, through the second LVDS transceiver 458, is in communicationwith the embedded PC CPU 100 and the Timer CPU 102 via the LVDS data bus18 and the first LVDS transceiver 104. In another embodiment, LVDS Isnot employed and the LVDS data bus 18 is replaced with an alternate busarchitecture. The VI CPU 450 executes software and/or firmware operableto respond to control inputs, for example from the controller module 14,and to generate one or more signals, for example output 466, to send tothe amplifiers 452.

The VI CPU 450 also executes software and/or firmware to monitoroverheat condition, waveform distortion, under-voltage condition andover-current condition by utilizing respective detectors associated withthe amplifiers 452 and power supply 456. The VI CPU 450 may take actionon a fault condition, such as removing DC power from the amplifiers 452when an overheat condition exists. The VI CPU 450 also sends controlsignals to the amplifiers 452, including voltage and current outputlevel controls. In an embodiment, the embedded PC CPU 100 configures theVI CPU 450 with a group of signal parameters. The feedback component 454may provide an analog feedback to the amplifier 452 which the amplifier452, or other analog feedback control circuitry (not shown), employed toadjust the output 460 to the appropriate level using analog closed loopfeedback control techniques. The feedback component 454 also providesdigital feedback to the VI CPU 450. The feedback component 454 or aseparate analog-to-digital converter (not shown) may convert the analogfeedback to the digital representation for transmission to the VI CPU450. The VI CPU 450 employs the digital feedback to adjust the signalsent by the VI CPU 450 to the amplifier 452 to drive the output 460 tothe appropriate level using digital closed loop feedback controltechniques. The use of both an analog feedback loop and a digitalfeedback loop provide for a more accurate output than either an analogfeedback loop by itself or a digital feedback loop by itself.

The VI power supply 456 is directly connected to the alternating current(AC) power mains (not shown) within the relay test device 10. The ACpower mains receive power from, for example, a power cord and plugconnected to external utility power. Placing the VI power supply 456 oneach VI generator 16 permits one VI generator 16 to fail, for examplethe first VI generator 16 a, while the other VI generators 16, forexample the second VI generator 16 b, the third VI generator 16 c, andthe fourth VI generator 16 d, continue to operate normally.Series-aiding output chokes 469 are used to filter digital poweramplifier switching noise from the output 466 and couples the returnsignal currents back to the amplifier 452 via a second winding of choke469. The amplifier output 452 is connected to the choke 469 input andthe choke output is connected to the output 466. The amplifier 452floats in reference to ground potential, and is removably referenced toground at the output of choke 469.

The amplifier 452 boosts the level of input signals to the levelsrequired to test relays. In one embodiment, the first amplifier 452 a isa current generator rated to produce a 200 VA power level and the secondamplifier 452 b is a voltage generator rated to produce a 150 VA powerlevel. In other embodiments, the amplifiers 452 may be rated to producemaximum power outputs in the range 50 VA to 500 VA. The second amplifier452 b may be convertible to a current generator. In other embodiments,other amplifier specifications may be supported. The output levels ofthe amplifiers 452 may be selectable to two or more range levels, forexample a high amplification level and a low amplification level. Theamplifier 452 may be sourced from the VI CPU 450 or from the optionalinput 468. In one embodiment, the amplifier 452 may be controlled tooutput of voltage or current, or a constant power level into a varyingexternal load.

Now turning to FIG. 10 b, in one embodiment, the present disclosureenables the constant power output 486 which provides a significantutility and simplicity to the test process with the capability todeliver a known constant or linear power output to the relay under test24. In one example, a test engineer may desire to test the relay undertest 24 at multiple tap positions. The first tap may require 2 amps at100 volts. The second tap may require 5 amps at 40 volts. The third tapmay require 10 amps at 20 volts. Without this capability of the voltageand current generators, the output is not linear nor constant 488. Itmay have several operational high points 490 and low points 492 inoutput performance curves, where the rated output power only exists inrestricted current, voltage or frequency values. In other combinationsof voltage, current or frequency, a great disparity of rated power andactual delivered power may exist. This means the test engineer will needto consult a table of performance for the relay test system, anddetermine if the system output is sufficient to perform the test. In thepreferred embodiment, the constant output power 486 assures thecombination of voltage and current will always yield the constant outputpower 486 if needed. No complex calculations or performance tables arenecessary, the voltage, current and thus power values may be calculatedmathematically.

Turning now to FIG. 11, a block diagram depicts a portion of thesoftware components operating on the VI CPU 450. A control component 500is in communication with and controls a signal look-up component 502, aDFR playback component 504, a signal generation component 506, and astreaming data playback component 508. The signal look-up component 502is associated with a plurality of data tables 510—a-first data table 510a, a second data table 510 b, and a third data table 510 c—eachcontaining data representing a periodic signal. Feedback from the outputof one of the amplifiers 452 may provide input to the control component500. In an embodiment, the analog feedback from the output of one of theamplifiers 452 is converted to 16 bits of digital feedback. Theanalog-to-digital conversion may be provided by the control component500 or by some analog-to-digital converter, not shown, between theamplifier 452 and the control component 500. In other embodiments,either more than 16 bits or less than 16 bits of digital feedback may beemployed. The control component 500 may employ the feedback to generatecontrol signals in accordance with closed loop feedback controlalgorithms known to one skilled in the art. The DFR playback component504 is associated with a plurality of DFR files 512—a first DFR file 512a, a second DFR file 512 b, and a third DFR file 512 c—each containingdata representing a digital fault recording. The control component 500selects, configures, and controls one or more of the signal look-upcomponent 502, the DFR playback component 504, the streaming dataplayback component 508, or the signal generation component 506 based oncommunication received from the controller module 14.

In an embodiment, the signal look-up component 502, the DFR playbackcomponent 504, the streaming data playback component 508, and the signalgeneration component 506 produce a digital signal which is output to theamplifier 452 to be amplified. In another embodiment, the signal look-upcomponent 502, the DFR playback component 504, the streaming dataplayback component 508, and the signal generation component 506 producedigital signals that may be summed together or otherwise combined, asfor example mixing, and the summed or combined digital signal is outputto the amplifier 452 to be amplified. The digital signal is converted toan analog signal by a DAC within the amplifier 452 or by a DAC (notshown) between the VI CPU 450 and the amplifier 452. The digital signal,taken at a particular time, is a number which proportionally representsthe amplitude of a desirable voltage or current signal at thatparticular time. The control component 500 periodically commands thatthe number be determined, for example at a 14.4 kHz periodic rate andhence approximately every 69.4 microseconds (uS) which may be termed thecalculation period. The 14.4 kHz periodic rate may be established by aclock interrupt being presented to the VI CPU 150 every 69.4 uS. Thecontrol component 500 may run inside a clock interrupt service routinewhich is invoked when the clock interrupt is presented to the VI CPU 150450.

In one embodiment, the VI generators 16 synchronize to a master clockgenerated by the controller module 14. However, since the signalgeneration component 506 is a mathematical derivation of Master Clock(MT1)=Vigen Signal Time (VST1)+n1, where n1 is the deviation desiredfrom MT1. The output signal can be skewed in phase based off of thereference of the master clock, such as one output phase stayingsynchronous with the master (MT1=VST1), creating a 60 Hz sine wave, andthe other skewing in phase, perhaps 30 degrees, so VST1=MT1+n1 happensjust once, thereafter VST1=MT1+the single quantity of n1, providing atime delay resulting in a phase skew that does not change. To furtherskew phase in relation to the Master Clock (MT1) another mathematicalexpression of n is derived to yield the change in phase desired, such asVST1=MT1+n1+n2. Another application of this would be a frequency ramp,whereas VST1=MT1+n1, whereas the addition of n1 is applied at everyinterrupt (i), so after three interrupts the sample point is output asVST1=MT1+n1*(3*i)). To return to the master clock, VST1 is set to MT1.

Turning now to FIG. 12, a block diagram depicts some of the softwarecomponents included in the signal generation component 506. The signalgeneration component 506 generates an arbitrary periodic test signalfrom real-time calculations. The approach of generating a test signalfrom real-time calculations supports generating many more kinds of testsignals than may be generated using other generation techniques. Theability to generate more kinds of test signals can be used to conductmore thorough and/or more realistic testing of relays.

The signal generation component 506 includes a plurality of waveformgenerators 550. In an embodiment, a plurality of outputs of the waveform generators 550 feed into a merge component 552 which combines theseveral signal components produced by the waveform generators 550. Inanother embodiment, the plurality of outputs of the wave form generators550 and the outputs of the signal look-up component 502, the DFRplayback component 504, and the streaming data playback component 508are combined in the merge component 552. The merge component 552 may suminputs, as for example adding the outputs of two or more wave formgenerators 550. The merge component 552 may mix inputs, as for examplemodulating a DFR signal output by the DFR playback component 504 onto a60 Hz sinewave signal output by one of the wave form generators 550. Themerge component 552 may sum inputs, mix inputs, and functionally combineinputs in other ways. An output of the merge component 552 feeds into anexponential damping component 554 which may exponentially dampen theoutput of the merge component 552. An output of the exponential dampingcomponent 554 feeds into a digital low pass filter 556 which mayselectively attenuate the high frequency signal components of the outputof the exponential damping component 554. In an embodiment, the outputof the digital low pass filter 556 may feed into a feedback controlcomponent 558 which provides an analog feedback control loop. In anembodiment, the digital output of the low pass filter 556 is convertedfrom a digital to an analog signal by the feedback control component558. In an alternate embodiment, a digital-to-analog converter, notshown, between the low pass filter 556 and the feedback controlcomponent 558 converts the digital output of the low pass filter 556 toprovide an analog signal to the feedback control component 558. Thefeedback control component 558 receives an analog feedback from theamplifier 452 and produces the input to the amplifier 452. The amplifier452 produces the output signal for testing the relay under test 24.

Alternately, the analog feedback control loop is closed by analogcontrol components within the amplifier 452 and the feedback controlcomponent 558 is not part of the signal generation component 506. Inthis embodiment, the output of the low pass filter 556 produces theinput to the amplifier 452. The amplifier 452 produces the output signalfor testing the relay under test 24.

In an embodiment, the plurality of waveform generators 550 includes afirst sine waveform generator 560, a second sine waveform generator 562,a third sine waveform generator 564, a fourth sine waveform generator566, a half-sine waveform generator 568, a square waveform generator570, and a DC level waveform generator 572. The DC level waveformgenerator 572 may provide a DC offset or a voltage offset. Each waveformgenerator 550 is initialized with functional arguments stored in anargument vector. In another embodiment, other orthogonal or logic basedfunctions known to the signal processing art may be employed to generatesignal components. This includes but is not limited to those signalsgenerated via simple tables, mathematical formulas, hybrid combinationsthereof, to those created via very complex algebraic formulas, such asused in Wavelet Theory or Fractal Signal Representation and other signalmixing and reproduction functions. The functional arguments and methodof implementation determine the waveforms generated by the waveformgenerators 550.

The group of argument vectors needed to initialize all of the waveformgenerators 550 are stored in an argument vector array 574. A pluralityof argument vector arrays 574—a first argument vector array 574-a, asecond argument vector array 574-b, and a third argument vector array574-c—are stored for use by the signal generation component 506. A widerange of argument values may be specified, enabling the signalgeneration component 506 to generate a large number of differentcomposed signals, providing useful flexibility for testing relays. In anembodiment, a 14.4 kHz interrupt clock frequency limits the maximumfrequency of generation of a periodic waveform signal to less than 7.2kHz, based on the Nyquist theorem, but in other embodiments a higherfrequency interrupt clock may support generating higher frequencywaveform signals.

In an embodiment, each signal generation component 506 is able to store128 independent argument vector arrays 574, but in other embodimentseither more or fewer independent argument vector arrays 574 may bestored. The control component 500 may select a different one of the 128independent argument vector arrays 574 to be active during eachcalculation period, thereby changing the signal components produced bythe waveform generators 550. By changing between several independentargument vector arrays 574 during a test, the signal generationcomponent 506 is able to produce a complex digital waveform for testing.

The first sine waveform generator 560, the second sine waveformgenerator 562, the third sine waveform generator 564, the fourth sinewaveform generator 566, the half-sine waveform generator 568, and thesquare waveform generator 570 are initialized with an amplitudeargument, a frequency argument, and a phase argument from the argumentvector 574 associated with each waveform generator 550. In anembodiment, the frequency arguments associated with the second sinewaveform generator 562, the third sine waveform generator 564, thefourth sine waveform generator 566, the half-sine waveform generator568, and the square waveform generator 570 may be constrained to be aharmonic frequency of the frequency argument of the first sine waveformgenerator 560. In another embodiment, however, the frequency argumentsmay not be constrained to be a harmonic frequency of the frequencyargument of the first sine waveform generator 560. Each waveformgenerator 550 may be completely autonomous from other waveformgenerators 550 by utilizing separate mathematical vectors. Each waveformgenerator 550 may be completely autonomous from the common fundamentalinterrupt clock frequency, instead being based on vectors provided tothe interrupt clock processor which may set a completely differentinterrupt clock speed.

The DC level waveform generator 572 is configured simply with anamplitude argument, as there is no frequency or phase associated with aconstant level signal. When the VI CPU 450 receives a clock interrupt, aclock interrupt service routine executes in which each of the waveformgenerators 550 calculates the value of the signal component associatedwith the waveform generator 550 and outputs the digital value of thesignal component to the merge component 552.

In an embodiment, the first sine waveform generator 560, the second sinewaveform generator 562, the third sine waveform generator 564, thefourth sine waveform generator 566, and the half-sine waveform generator568 may calculate discrete sinusoidal signals or segments of discretesinusoidal signals based on a series expansion summation algorithm whichemploys a first approximation looked up in a data table. For example, atable of sine values for 0, 10, 20, 30, 40, 50, 60, 70, 80, and 90degrees may be employed to look-up a first approximation of sin(Θ).Selecting a good first approximation of sin(Θ) will lead to the seriesexpansion summation algorithm converging quickly on an accuratesolution. In other embodiments, other methods for calculating discretesinusoidal signals or segments of discrete sinusoidal signals well knownto those skilled in the art may be employed.

The exponential damping component 554 calculates a damping coefficienta^(n), which the exponential damping component 554 multiplies with theoutput of the merge component 552 to produce the output of theexponential damping component 554. In practice, a computer program maycalculate the damping coefficient a^(n) as a(a^(n-1)), where (a^(n-1))is the previously calculated value of the damping coefficient. Forexample, the values of (1/2)n can be calculated as:(0.5)⁰=1(0.5)¹=0.5(1)=0.5=a ¹ =a(a ⁰)(0.5)²=0.5(0.5)=0.25=a ² =a(a ¹)(0.5)³=0.5(0.25)=0.125=a ³ =a(a ²)(0.5)⁴=0.5(0.125)=0.0625=a ⁴ =a(a ³)

The value of a is a positive real number equal to or less than 1. If ais equal to 1, the damping coefficient a^(n) will remain 1, effectivelyturning off the exponential damping component 554. In FIG. 12, theswitch bypassing the exponential damping component 554 illustrates thisconcept of turning off or bypassing the exponential damping component554. In an embodiment, the software implementing the exponential dampingcomponent 554 may respond to an argument value of 1 for a by simplyoutputting the digital value presented to the input of the exponentialdamping component 554. The value of a is stored in the argument vectorarray 574. In some embodiments, another method of calculating anexponential damping function known to those skilled in the art may beemployed. The exponential damping component 554 may be useful forproviding a relay test signal that models a short circuit transient.

The low pass filter component 556 is a digital filter whichmathematically attenuates high frequency content in the digital outputfrom the exponential damping component 554. The frequency cut-off of thelow pass filter component 556, the frequency at which the low passfilter component 556 attenuates the power of a frequency component tohalf its original value (or 0.7 times the value of the voltage orcurrent amplitude of the frequency component), is controlled by a tauparameter which is stored in the low pass filter component and isindependent of the argument vector arrays 574. In an embodiment, the tauparameter represents a time constant of the low pass filter. A widevariety of digital filters are known to those skilled in the art,including finite impulse response type filters, auto regressive movingaverage filters, and digital filter designs obtained by transforminganalog designs. All of these low pass filter designs are contemplated bythe present disclosure. The low pass filter component 556 may provideuseful smoothing of the digital signal when changing between independentargument vector arrays 574 as described above, or smoothing any suddenchange of the fundamental signal itself. The output of the amplifier 452may be selected to different boost ranges, and the tau parameter may bea different value during the range change transition. The low passfilter component 556 may be disabled or bypassed, a concept illustratedin FIG. 12 by a switch bypassing the low pass filter component 556.

In one embodiment, the signal components, the summation of the signalcomponents, the exponential damping processing, the low pass filtering,and the feedback control calculations are calculated during eachcalculation period or clock interrupt service routine to produce thegenerated signal output.

Returning to FIG. 11, the DFR playback component 504 plays-back the DFRfile 512 which may contain the digital recording of a fault experiencedby a relay in the field. The DFR file 512 is loaded from an externalsource into the controller module 14, for example from a laptopcomputer, a workstation, or downloaded via the Internet. The controllermodule 14 sends the DFR file 512 with other control information to theVI generator 16. During the clock interrupt service routine, the DFRplayback component 504 reads the appropriate value of the DFR signal outof the DFR file 512 and outputs that value as the number representingthe digital signal at that moment in time. Multiple DFR files 512 may beloaded from an external source into the controller module 14 andthereafter forwarded with other control information to the VI generator16. These multiple DFR files 512 may be concatenated or playedback-to-back.

In some cases the sampling frequency of the DFR file 512 may not matchthe clock interrupt frequency presented to the VI CPU 450. For example,the clock interrupt frequency presented to the VI CPU 450 may be 14.4kHz while the sampling frequency employed to record the DFR file 512 maybe 12.335 kHz. Playing back the 12.335 kHz DFR file 512 at 14.4 kHzwould result in frequency shifting the entire frequency spectrum of theDFR file 512 up by 17%, which is generally undesirable.

In an embodiment, the content of the DFR file 512 may be mathematicallyconverted for play-back at 14.4 kHz. The DFR file 512 may be convertedto a higher frequency digital signal which is a multiple of the samplingfrequency of the DFR file 512 and the nominal clock interrupt frequency.In this case, new data points which occur between the original sampleddata may be calculated by linearly interpolating between the originalsampled data. Alternately, another mathematical interpolation techniqueknown to those skilled in the art may be employed. The higher frequencydigital signal may then be played back, selecting those data points thatmatch the nominal clock interrupts and ignoring those data points thatdo not match the nominal clock interrupts. In an embodiment, onselection of the associated test procedure, as a test initializationactivity, the DFR file 512 may be processed using this approach toproduce an interpolated version of the DFR file 512, based on thenominal interrupt clock frequency, and when the test executes theinterpolated version of the DFR file may be played back. Thismathematical solution, however, may present an excessive processing loadin some embodiments.

Synchronization of Sampling to Playback Frequency

An alternate solution to play-back of the DFR file 512 that has beenrecorded at an incompatible sampling frequency is to adjust the clockinterrupt frequency presented to the VI CPU 450 to accord with thesampling frequency of the DFR file 512. As the VI CPU 450 may becomposed of multiple processors, FPGAs, DSPs, CPLDs, and ASICS, only theclock interrupt sent to the device or devices involved in generating thestream of signal values needs to be frequency adjusted. When the clockinterrupt frequency is adjusted in this way, the clock interrupt serviceroutine executes at the sampling frequency, and the playback reproducesthe originally recorded signal. To support this capability, a DFR testmay be configured by identifying the DFR file 512 and the desired clockinterrupt frequency for the DFR test employing the UI 20. In anembodiment, the clock interrupt frequency may be changed arbitrarily atany time.

Turning now to FIG. 13, a playback device 600 that employs an adjustableclock interrupt frequency is depicted. The playback device 600 includesa playback processor 602, a digital recording 604, and an interruptclock 606 containing a clock interrupt frequency parameter 608. Theinterrupt clock 606 generates an interrupt clock signal at a frequencydetermined by the interrupt frequency parameter 608, for example at12.335 kHz. The interrupt clock signal is received by the playbackprocessor 602, causing the playback processor 602 to execute a clockinterrupt service routine. In the clock interrupt service routine, adata sample in the digital recording 604 is read and played back toproduce a playback signal that is output by the playback device 600.

The playback signal may be an analog output produced by processing thedata sample and converting to an analog signal for output. The playbacksignal may be a digital output produced directly from the data sample orbased on processing the data sample, for example after digitallyfiltering the stream of data samples to selectively enhance one or moreranges of frequency content and to selectively attenuate one or morealternate ranges of frequency content. The ability to adjust theinterrupt clock 606 in this way to coordinate the sampling frequencywith the playback frequency has utility for devices which playbackdigital recordings which may be recorded at arbitrary frequencies.

In an embodiment, the playback processor 602 determines the samplingfrequency of the digital recording 604 by reading data stored with thedigital recording 604 or by analyzing the content of the digitalrecording 604. In another embodiment, a UI 610 is in communication withthe playback device 600, and the UI 610 provides the sampling frequencyto the playback processor 602. The playback device 600 sends the clockinterrupt frequency parameter 608, based on the sampling frequency ofthe digital recording 604, to the interrupt clock 606. The clockinterrupt frequency parameter 608 may be an integer multiple of thesampling frequency of the digital recording 604, for example one timesthe sampling frequency, two times the sampling frequency, or 16 timesthe sampling frequency.

Turning now to FIG. 14, a flow chart depicts a method for adjusting aninterrupt clock for playing back a digital recording 604. In block 650the sampling frequency of the digital recording 604 is determined. Thesampling frequency of the digital recording 604 may be embedded in thedigital recording 604 itself or may be associated with the format orprotocol of the digital recording 604. Alternately, the samplingfrequency of the digital recording 604 may be supplemental informationprovided to a playback device 600, for example data provided to therelay test device 10. The method proceeds to block 652 where thesampling frequency is used to adjust the interrupt clock frequency ofthe playback device 600. The interrupt clock frequency of the playbackdevice 600 may be adjusted to an integer multiple of the samplingfrequency, for example the same frequency as the sampling frequencywherein the integer multiple is one.

The method proceeds to block 654 where the playback device 600 reads adata sample from the digital recording 604. The method proceeds to block656 where the playback device 600 converts the data to a useful form,for example converting the data to an analog output suitable to drive anaudio speaker or to drive the relay under test 24. The method proceedsto block 658 where if the digital recording 604 has not completedplayback, the method proceeds on to block 660. In block 660 the methodwaits until the next clock interrupt is generated and then returns toblock 654. The method loops through block 654, 656, 658, and 660 untilthe digital recording 604 has been completely played back. In block 658when playback of the digital recording 604 has completed, the methodexits.

This method may be employed by the relay test device 10 to playback DFRswhich were recorded at a sampling rate different from a nominalinterrupt clock frequency of the VI CPU 450. More generally, this methodmay be useful for playing back any digital recording 604 where thesampling frequency of the digital recording 604 is different from anominal interrupt clock frequency of the playback device 600.

Returning to FIG. 11, the signal look-up component 502 is associatedwith a data table 510 which stores a periodic signal in memory. Ratherthan calculate the value of the periodic signal in each calculationperiod, each of the values of the periodic signal over a complete cycleof the period of the signal are pre-computed, stored in memory, andrepeatedly played back in sequence. The data table 510 may be calculatedby the VI CPU 150 as an initialization operation when commanded by thecontroller module 14, may be calculated by the controller module 14 andsent with other control information to the VI CPU 150, or may becalculated external to the relay test device 10 and loaded along withtest definitions. The signal look-up component 502 may providecompatibility with legacy testing procedures. The signal look-upcomponent 502 reads the appropriate value of the periodic signal andoutputs that value as a binary number.

The streaming data playback component 508 plays-back a streaming datainput, much as the DFR component 504 plays back a DFR file 512. Thefunctionality provided by the streaming data playback component 508 isuseful when, for example, a desirable playback recording is too long forstoring and reading back from a file. The streaming data is received byone of the interfaces of the relay test device 10, such as at anEthernet interface, and directed to the controller module 14. Thecontroller module 14 may perform flow control on the streaming data toavoid overflowing buffers in the streaming data playback component 508.The controller module 14 sends the streaming data over the LVDS bus 18to the VI generator 16. The streaming data flows to the VI CPU 450 andthence to the streaming data playback component 508. The streaming dataplayback component 508 may perform various processing of the streamingdata including attenuating selected frequencies or frequency ranges,boosting selected frequencies or frequency ranges, phase shifting thestreaming data, and other transformations known to those skilled in theart. Some of this processing may be performed by the embedded PC CPU 100in the controller module 14 before the controller module 14 sends thestreaming data over the LVDS bus 18 to the VI generator 16.

Hand-held Controller for Relay Test Device

Turning now to FIG. 15, a block diagram of a touch view interface (TVI)700 is depicted. As mentioned above, in one embodiment the TVI 700fulfills the role of the UI 20. In an embodiment, the TVI 700 may bepermanently attached to the enclosure 22. In another embodiment, the TVI700 may be remotely connected via wireless means, such as radiofrequency or infrared communications. In another embodiment, the TVI 700may be tethered to the enclosure 22 by a removable cable which provideselectronic signals or fiber optic light signals to the TVI 700.

The TVI 700 may be employed to select test procedures or test programsfrom a menu of available test procedures, to configure test procedureparameters, to display test outputs or test inputs dynamically duringthe execution of a test procedure, and to display test results. The TVI700 may also be used to view and manage files stored on the relay testdevice 10, for example test log files. The dynamic display of testoutputs or test inputs during the execution of the test procedure may betermed a real-time display of metered voltage, current, phase, andfrequency. This real-time display feature may be employed by the testoperator to verify a valid test environment and to verify the appliedcharacteristics or test outputs while testing.

The TVI 700 includes a TVI CPU 702, a display component 704, a touchpanel component 706, and a control knob 708. The TVI CPU 702 maycomprise one or more DSPs, FPGAs, PLDs, CPLDs, ASICs, uPs, and uCs or acombination thereof. The TVI CPU 702 may be in communication with memorycomponents including RAM, ROM, EPROM, EEPROM, and/or flash. Theversioned programs 428 may be installed in the memory components or usedto re-program the TVI CPU 702 using the software/firmware installationsystem described above. In an embodiment, the TVI CPU 702 is implementedas a single CPLD.

The TVI CPU 702 communicates with the relay test device 10 to receivedisplay control signals and to return inputs from the touch panel 706and from the control knob 708. In this embodiment, the intelligenceneeded to manage files and to navigate menus resides in the relay testdevice 10. In another embodiment, this intelligence may reside in theTVI CPU 702.

In an embodiment, the TVI CPU 702 communicates with the relay testdevice 10 using LVDS. In other embodiments, the TVI CPU 702 and relaytest device 10 may communicate using optical, spread spectrum wireless,orthogonal frequency division multiplexing (OFDM) wireless, infrared,and high voltage level signals developed using voltage steppers or othervoltage boosting mechanism, or a combination thereof. The control knob708 combines a rotary control and a pushbutton control in one combineddevice. The rotary control may be employed to ramp test control values,such as ramping commanded voltage from 1 volt to 5 volts.

The touch panel component 706 physically overlays the display component704, as indicated by the dashed lines in FIG. 15. The display component704 is based on liquid crystal display (LCD) technology. The lightemitted by the display component 704 passes through the touch panelcomponent 706. The TVI CPU 702 sends a backlight brightness controlsignal and a LCD contrast control signal to the display component 704.The TVI CPU 702 sends a digital video signal to the display component704 whereby the display component 704 is painted with an image orscreen. The TVI CPU 702 stores the last known contrast and brightnessvalues when the TVI CPU 702 is powered down. The TVI CPU 702 recalls thestored contrast and brightness values during power up and uses thesevalues until receiving control signals from the relay test device 10. Inan embodiment, the TVI CPU 702 maps a transistor transistor logic (TTL)video signal received from the relay test device 10 to generate the LCDcontrast control signal. The TVI CPU 702 updates the display component704, which also may be referred to as painting the display component704, in real-time. In an embodiment, the display component 704 provideshigh-resolution graphics capabilities.

The touch panel component 706 is based on thin film transistortechnology. The TVI CPU 702 periodically reads or polls the touch panelcomponent 706 to receive inputs and sends the inputs of the touch panelcomponent 706 to the relay test device 10. The TVI CPU 702 alsoperiodically reads or polls the control knob 708 and sends the inputs ofthe control knob 708 to the relay test device 10. The control knob 708is operable to provide an on/off indication activated by pressing in onthe control knob 708 like a push-button switch and to provide a variableindication activated by rotating the control knob 708 clockwise orcounterclockwise.

The TVI 700 is ruggedized for use in a harsh environment. The outershell of the TVI 700 is a durable material. In an embodiment, thematerial of the outer shell of the TVI 700 is vacuum-formed ABS plastic.The internal devices are mounted in mechanical shock absorbing foam. Thecontrol knob 708 is the only moving part on the TVI 700. In anembodiment, the TVI 700 may include one or more maintenance interfacesto support calibration and/or testing the TVI 700. The maintenanceinterfaces may include RS-232, RS-422, Joint Test Action Group (JTAG),USB, GPIB, wireless, IEEE-1394, and Ethernet interfaces. In anembodiment, the TVI 700 communicates with the relay test device 10through a cable and receives electrical power from the relay test device10 through the cable.

Turning now to FIG. 16, a manual test screen 750 which may be displayedby the TVI 700 is depicted. The manual test screen 750 illustratesseveral of the display and control capabilities of the TVI 700. A VItable 752 provides a real-time display of voltage and current parametersincluding magnitude, phase angle, and frequency which are output by theVI generators 16. A radial display 754 provides a real-time graphicdisplay of voltage and current magnitude and phase wherein magnitude andphase angle are depicted by a phasor, for example a I1 phasor 756. Themagnitude may be proportional to the length of the phasor, and the phaseangle is indicated by the angle of the phasor. Several touch screenbuttons 758 are operable to activate test functions or to selectdifferent screens. The TVI 700 may be operable to display in color tohighlight active signals or signals out of limits. The currently activestate indicator of the group of test state indicators 760, for example,may illuminate as a color appropriate to the testing application. Forexample, green may signify selected but not active. Red may indicateactive and user attention is desirable to avoid danger. Red may alsoindicate a fault. The test state indicators 760 further promote userinput of various fault states applied to relay under test 24. Otherscreens may display theoretical versus actual values of parameters. Themanual test screen 750 is only exemplary, and other screens and viewsare contemplated for the TVI 700.

The TVI 700 may be employed to display a schematic drawing or a bitmapped digital image of the relay under test 24 and patch cablesconnecting the relay test device 10 to the relay under test 24 tofacilitate initial test setup.

In one embodiment, a programming language and associated operationenvironment, such as Megger AVTS proprietary programming language andoperation environment, may be used to define, set up, monitor, store,and analyze relay test procedures. The programming language and theassociated operation environment may be operative on a laptop computer,a personal computer, the relay test device 10, or the TVI 700. An onlineramp control capability may be employed to perform traditionalsteady-state tests by applying test quantities to the device under testand automatically ramping the current, voltage, phase angle, and/orfrequency. Using either the online ramp or a vector controls capability,dynamic tests can be performed which may include setting a pre-faultcondition and allowing the software to automatically test/search for theoperating characteristic of the relay under test 24 by selecting one ofseveral available methods. A plurality of test wizards, or test modules,may be selected from pull-down menus. Test wizards guide personnelthrough step-by-step procedures to create relay test procedures.

The online vector control provides direct control of the relay testsystem 10. Up to sixteen vector states, for example, may be created andplayed back through the relay test system 10. A timer control isavailable to enable starting the relay test system 10 timer at theexecution of any one of the vector states. The timer stop is typicallycontrolled by an action from one of the outputs of the relay under test24 connected to the appropriate programmed input of the relay testsystem 10.

The online ramp control provides direct real-time control of the relaytest system 10. This control is similar to the online vector control,but the online ramp control provides automatic ramping of selectedoutputs to do pick-up or drop-outs tests of amplitude, phase angle,and/or frequency. A timer control is available to enable starting one ofthe timers of the relay test system 10 at the execution of either of theramp states. The timer stop is typically controlled by an action fromone of the outputs of the relay under test 24 connected to the timerstop gate.

Test wizards are available for the most common types of relays includingover-current, over/under voltage, frequency, differential, distance,synchronizing, and directional. The over-current wizard providesautomatic pickup, instantaneous pickup, and timing. IEEE and IEC timecurve algorithms are provided for automatic evaluation of test results.Digitized time curves for various electromechanical over-current relaysare also available. A DC target and seal-in test is available to testNorth American relays. The over/under voltage wizard provides automaticpickup and timing. The frequency wizard provides automatic pickup andtiming tests for over or under frequency relays. The differential wizardperforms automatic winding pickup, differential characteristic (slope)test and harmonic restraint tests. The distance wizard performsautomatic reach, max angle of torque, and characteristic tests on singlephase, three phase, open delta, or three phase Y connected relays. Theuser may choose between fixed voltage and vary current or fixed currentand vary voltage. In addition, the user may select basic distancecharacteristics using a pull-down menu. A test report will providepass/fail information of the test results based on user input for eachof the over-current wizard, the over/under voltage wizard, the frequencywizard, the differential wizard, and the distance wizard. It will beappreciated that the present disclosure includes comprehensiveprogramming and software to define, set-up, initiate, monitor, andanalyze relay tests.

In one embodiment, a scripting language is employed to providefunctionality which does not require compilation. Scripts developedusing the scripting language are embedded into a relay test module whichis a procedural test methods file that the software uses to know how tointeract with and to direct test system 10 to test the relay under test24. The scripting language includes the ability to communicate withexternal devices using interfaces such as RS232, USB, GPIB, and otherinterfaces. The scripts may be called from within the relay test module,in the execution environment. In an embodiment, the scripting languageis VBScript, but other scripting languages may be employed in otherembodiments, such as Perl or a proprietary scripting language developedspecifically for use with the relay test device 10.

While several embodiments have been provided in the present disclosure,it should be understood that the disclosed systems and methods may beembodied in many other specific forms without departing from the spiritor scope of the present disclosure. The present examples are to beconsidered as illustrative and not restrictive, and the intention is notto be limited to the details given herein, but may be modified withinthe scope of the appended claims along with their full scope ofequivalents. For example, the various elements or components may becombined or integrated in another system or certain features may beomitted, or not implemented.

Also, techniques, systems, subsystems and methods described andillustrated in the various embodiments as discrete or separate may becombined or integrated with other systems, modules, techniques, ormethods without departing from the scope of the present disclosure.Other items shown as directly coupled or communicating with each othermay be coupled through some interface or device, such that the items mayno longer be considered directly coupled to each but may still beindirectly coupled and in communication with one another. Other examplesof changes, substitutions, and alterations are ascertainable by oneskilled in the art and could be made without departing from the spiritand scope disclosed herein.

1. A test device for testing relays, comprising: a chassis; a pluralityof generator components removably coupled to the chassis, each of theplurality of generator components comprising: a signal generator, a CPUto promote test signal generation by the signal generator, and one ormore amplifiers to amplify signals generated by the signal generator;and a controller coupled to communicate with the plurality of generatorcomponents.
 2. The test device of claim 1 wherein each of the pluralityof generator components further comprise a power supply to power theassociated signal generator.
 3. The test device of claim 1 wherein eachof the plurality of generator components are further defined asconfigured to modularly couple and uncouple from the chassis for removalfrom the chassis when one of the plurality of generator componentsfails.
 4. The test device of claim 3 wherein the chassis is defined asan enclosure enclosing the plurality of generator components.
 5. Thetest device of claim 1 wherein plurality of generator components isfurther defined as three generator components, each coupleable tocommunicate with one of three phases for testing relays.
 6. The testdevice of claim 1 wherein the plurality of generator components isfurther defined as four generator components, each one of three of thegenerator components operable to communicate with at least one of threephases for testing relays, the fourth generator component operable fortesting and redundancy in the event of failure of one of the othergenerator components.
 7. The test device of claim 6 wherein thecontroller is operable to redirect signal generation by one of thegenerator components in the event of failure by another of the generatorcomponents.
 8. The test device of claim 1 wherein each signal generatoris further defined to include a voltage generator and a currentgenerator.
 9. The test device of claim 1 wherein the amplifier on eachof the plurality of generator components is further defined as twoamplifiers, one amplifier per signal generator.
 10. The test device ofclaim 1 further comprising a storage device in communication with thecontroller and operable to store information.
 11. The test device ofclaim 10 wherein the information storable on the storage deviceincludes, signal information used to generate test signals to testrelays.
 12. The test device of claim 10 wherein the information storableon the storage device includes relay testing information.
 13. The testdevice of claim 10 wherein the information storable on the storagedevice includes correction and offset factors employed to correctimperfections in the uncorrected output, thereby calibrating the outputsystem to very favorable accuracies referencing standards.
 14. A methodfor testing a relay using a relay test device, comprising: generating,by a plurality of modular signal generation components of the relay testdevice, test signals to test the relay; identifying a failure by one ofthe plurality of modular signal generation components; removing thefailed one of the plurality of modular signal generation components fromwithin an enclosure of the relay test device; while the failed one ofthe modular signal generation components is removed from the enclosureof the relay test device, generating, by the remaining modular signalgeneration components, test signals to test the relay; obtaining aworking modular signal generation component; installing the workingmodular signal generation component in the enclosure of the test device;and generating, by at least the working modular signal generationcomponent, test signals to test the relay.
 15. The method of claim 14wherein each of the modular signal generation components comprises: asignal generator; a power supply to power the signal generator; a CPU topromote test signal generation, by the signal generator; and anamplifier to amplify signals generated by the signal generator.
 16. Themethod of claim 14 further comprising repairing the failed modularsignal generation component.
 17. The method of claim 14 furthercomprising replacing the failed modular signal generation component. 18.A system for testing a relay, comprising: a signal generator operable togenerate at least one test signal; an amplifier operable to receive thetest signal from the signal generator and amplify the test signal, andthe amplifier further operable to output the test signal to the relay totest the relay; and a controller module programmable with a relay testprocedure, the controller module in communication with the signalgenerator to promote the signal generator generating test signals basedon the relay test procedure, the controller module further operable tomonitor a state of the relay and to determine a results of the relaytest.
 19. The system of claim 18 wherein the amplifier is a component ofthe signal generator and wherein each signal generator includes acentral processing unit and a direct current power supply that receivespower from an alternating current power source.
 20. The system of claim19 wherein the signal generator includes two amplifiers and is operableto generate two signals.
 21. The system of claim 19 wherein thecontroller module communicates with the signal generators using lowvoltage differential signaling.
 22. The system of claim 18 furtherincluding a plurality of programmable inputs and programmable outputs incommunication with the controller module and wherein the controllermodule is operable to monitor the plurality of programmable inputs. 23.The system of claim 18 wherein the controller module is further operableto request and receive one or more settings of the relay and to commandthe relay to change the settings to a desirable value.
 24. The system ofclaim 18 wherein the system further includes a storage device operableto store a digital fault recording, the controller module operable tocommunicate the stored digital fault recording to the signal generatorto prompt the signal generator to play-back the digital fault recordingto test the relay.
 25. The system of claim 18 wherein the controllermodule is further operable to receive from an external source streamingdata and to communicate the streaming data to the signal generator forthe signal generator to playback the streaming data as the test signal.26. The system of claim 25 wherein the controller module is furtheroperable to negotiate flow control of the streaming data with theexternal source.
 27. The system of claim 25 wherein the controllermodule is further operable to process the streaming data.
 28. The systemof claim 27 wherein the controller module is operable to provideadditional manipulation of the streaming data.
 29. The system of claim27 wherein the controller module and a central processing unit coupledto communicate with the signal generator are operable to provideadditional manipulation of the streaming data.
 30. The system of claim27 wherein a central processing unit coupled to communicate with thesignal generator is operable to modify an element of the streaming data.31. The system of claim 18 further including a battery simulator DCoutput operable to supply power to the relay.
 32. The system of claim 18further including analog input in communication with the amplifier,wherein the analog input is selectable for output to test the relay. 33.The system of claim 18 wherein the amplifier is capable of producing avoltage signal of at least 150 voltamps and a current signal of at least200 voltamps simultaneously.
 34. The system of claim 18 wherein theamplifier is capable of producing a voltage signal of at least 150voltamps and a current signal of at least 200 voltamps independently.35. The system of claim 18 wherein the central processing unit includesa digital signal processor, a field programmable logic device, a complexprogrammable logic device, an and a microprocessor.
 36. The system ofclaim 17 wherein the signal generator is further defined as including avoltage and current generator operable to generate 150 voltamps voltageand 200 voltamps current.